This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This research project is part of an Alzheimer's Disease Research Center (ADRC) grant awarded in 2005. The major goal of this work is to determine whether sensitive behavioral tasks, together with eye-tracking technology, will reveal a profile of performance in MCI patients that is useful in predicting the onset of Alzheimer's disease. The overall plan is to test 60 MCI patients, 60 matched normal control (NC) subjects, 30 patients with Alzheimer's Disease (AD) and a group of 30 Parkinson's Disease patients without dementia (PD). All subjects have been recruited from the ADRC Clinical Core. Each subject is tested annually. We have successfully administered the preferential looking task together with eye-tracking in these subjects and are currently collecting Year 4/Year 5 data. An important contribution from this work would be the ability to diagnose sooner than is now possible in MCI patients oncoming cognitive decline, at a time when the nervous system is less compromised and, accordingly, more likely to benefit from therapeutic intervention. It is useful to note that the task we are using in our patient populations to detect early memory impairment is the same task we first developed for use in nonhuman primates for detecting damage to the hippocampus. Indeed, this task, called the Preferential Looking Task, when combined with eyetracking technology, has turned out to be one of the most sensitive tasks we now have for assessing memory dysfunction in both human and nonhuman primates.